Motor, rotor, compressor, and refrigeration and air conditioning apparatus

Abstract

A motor includes a stator, a rotor including a rotor core having a magnet insertion hole, and a plurality of permanent magnets disposed in the magnet insertion hole of the rotor core and having two permanent magnets adjacent to each other. The rotor core has a first magnet holding portion in the magnet insertion hole, and a second magnet holding portion at an end of the magnet insertion hole in a circumferential direction. The rotor core has a plurality of electromagnetic steel sheets stacked in an axial direction. Relationships A>B and A>C are satisfied, where a number of the plurality of electromagnetic steel sheets is represented by A, a number of electromagnetic steel sheets having the first magnet holding portions is represented by B, and a number of electromagnetic steel sheets having the second magnet holding portions is represented by C.

What is claimed is: 
     
       1. A motor comprising a stator and a rotor provided inside the stator, the rotor comprising:
 a rotor core having a magnet insertion hole, and 
 a plurality of permanent magnets disposed in the magnet insertion hole of the rotor core and having two permanent magnets adjacent to each other, 
 wherein the rotor core has a first magnet holding portion disposed between the two permanent magnets adjacent to each other in the magnet insertion hole, and a second magnet holding portion disposed at an end of the magnet insertion hole in a circumferential direction of the rotor core; 
 wherein the rotor core has a plurality of electromagnetic steel sheets stacked in an axial direction, and 
 wherein relationships A>B and A>C are satisfied, where a number of the plurality of electromagnetic steel sheets of the rotor core is represented by A, and among the plurality of electromagnetic steel sheets of the rotor core, a number of electromagnetic steel sheets having the first magnet holding portions is represented by B, and a number of electromagnetic steel sheets having the second magnet holding portions is represented by C. 
 
     
     
       2. The motor according to  claim 1 ,
 wherein each of the first magnet holding portion and the second magnet holding portion is a protrusion formed in the magnet insertion hole. 
 
     
     
       3. The motor according to  claim 1 , wherein the first magnet holding portion and the second magnet holding portion are disposed on an inner side of the magnet insertion hole in a radial direction of the rotor core. 
     
     
       4. The motor according to  claim 1 , wherein a relationship B=C is further satisfied. 
     
     
       5. The motor according to  claim 4 , wherein the plurality of electromagnetic steel sheets of the rotor core comprises:
 a first electromagnetic steel sheet having the first magnet holding portion and the second magnet holding portion, and 
 a second electromagnetic steel sheet having neither the first magnet holding portion nor the second magnet holding portion. 
 
     
     
       6. The motor according to  claim 1 , wherein a relationship C>B is further satisfied. 
     
     
       7. The motor according to  claim 6 , wherein the plurality of electromagnetic steel sheets of the rotor core comprises:
 a first electromagnetic steel sheet having the first magnet holding portion and the second magnet holding portion; 
 a second electromagnetic steel sheet having neither the first magnet holding portion nor the second magnet holding portion, and 
 a third electromagnetic steel sheet having the second magnet holding portion but having no first magnet holding portion. 
 
     
     
       8. The motor according to  claim 1 , wherein the plurality of electromagnetic steel sheets of the rotor core comprises:
 a first electromagnetic steel sheet having the first magnet holding portion and the second magnet holding portion; 
 a second electromagnetic steel sheet having neither the first magnet holding portion nor the second magnet holding portion; 
 a third electromagnetic steel sheet having the second magnet holding portion but having no first magnet holding portion, and 
 a fourth electromagnetic steel sheet having the first magnet holding portion but having no second magnet holding portion. 
 
     
     
       9. The motor according to  claim 1 , wherein, among the plurality of electromagnetic steel sheets of the rotor core, the electromagnetic steel sheet disposed at least one end of the rotor core in a stacking direction has at least one of the first magnet holding portion and the second magnet holding portion. 
     
     
       10. The motor according to  claim 1 , wherein each of the plurality of permanent magnets is a rare earth magnet containing neodymium (Nd), iron (Fe) and boron (B) as principal components, and
 exhibits a residual magnetic flux density in a range from 1.27 T to 1.42 T at 20° C. and a coercivity in a range from 1671 kA/m to 1922 kA/m at 20° C. 
 
     
     
       11. The motor according to  claim 1 , wherein the magnet insertion hole has a V-shape such that a center portion of the magnet insertion hole in the circumferential direction protrudes inward in a radial direction of the rotor core. 
     
     
       12. The rotor according to  claim 1 , wherein the magnet insertion hole extends straight, and the plurality of the permanent magnets comprises two permanent magnets. 
     
     
       13. The motor according to  claim 1 , wherein the plurality of permanent magnets comprises three permanent magnets. 
     
     
       14. The motor according to  claim 1 , wherein the rotor core has an opening on an inner side of the first magnet holding portion in a radial direction;
 wherein the rotor core has a center hole at a center in the radial direction, and 
 wherein a distance from the opening to the magnet insertion hole is shorter than a distance from the opening to the center hole. 
 
     
     
       15. A rotor comprising:
 a rotor core having a magnet insertion hole, and 
 a plurality of permanent magnets disposed in the magnet insertion hole of the rotor core and having two permanent magnets adjacent to each other, 
 wherein the rotor core has a first magnet holding portion disposed between the two permanent magnets adjacent to each other in the magnet insertion hole, and a second magnet holding portion disposed at an end of the magnet insertion hole in a circumferential direction of the rotor core; 
 wherein the rotor core has a plurality of electromagnetic steel sheets stacked in an axial direction, and 
 wherein relationships A>B and A>C are satisfied, where a number of the plurality of electromagnetic steel sheets of the rotor core is represented by A, and among the plurality of electromagnetic steel sheets of the rotor core, a number of electromagnetic steel sheets having the first magnet holding portions is represented by B, and a number of electromagnetic steel sheets having the second magnet holding portions is represented by C. 
 
     
     
       16. A compressor comprising a motor and a compression mechanism driven by the motor,
 the motor comprising a stator and a rotor provided inside the stator, 
 the rotor comprising: 
 a rotor core having a magnet insertion hole, and 
 a plurality of permanent magnets disposed in the magnet insertion hole of the rotor core and having two permanent magnets adjacent to each other, 
 wherein the rotor core has a first magnet holding portion disposed between the two permanent magnets adjacent to each other in the magnet insertion hole, and a second magnet holding portion disposed at an end of the magnet insertion hole in a circumferential direction of the rotor core; 
 wherein the rotor core has a plurality of electromagnetic steel sheets stacked in an axial direction, and 
 wherein relationships A>B and A>C are satisfied, where a number of the plurality of electromagnetic steel sheets of the rotor core is represented by A, and among the plurality of electromagnetic steel sheets of the rotor core, a number of electromagnetic steel sheets having the first magnet holding portions is represented by B, and a number of electromagnetic steel sheets having the second magnet holding portions is represented by C. 
 
     
     
       17. A refrigeration and air conditioning apparatus comprising a compressor, a condenser, a decompression device and an evaporator,
 the compressor comprising a motor and a compression mechanism driven by the motor, 
 the motor comprising a stator and a rotor provided inside the stator, 
 the rotor comprising: 
 a rotor core having a magnet insertion hole, and 
 a plurality of permanent magnets disposed in the magnet insertion hole of the rotor core and having two permanent magnets adjacent to each other, 
 wherein the rotor core has a first magnet holding portion disposed between the two permanent magnets adjacent to each other in the magnet insertion hole, and a second magnet holding portion disposed at an end of the magnet insertion hole in a circumferential direction of the rotor core; 
 wherein the rotor core has a plurality of electromagnetic steel sheets stacked in an axial direction, and 
 wherein relationships A>B and A>C are satisfied, where a number of the plurality of electromagnetic steel sheets of the rotor core is represented by A, and among the plurality of electromagnetic steel sheets of the rotor core, a number of electromagnetic steel sheets having the first magnet holding portions is represented by B, and a number of electromagnetic steel sheets having the second magnet holding portions is represented by C.